THE INFLUENCE OF SOIL MOISTURE STRESS ON THE GROWTH AND GAS EXCHANGE CHARACTERISTICS OF YOUNG HIGHBUSH BLUEBERRY PLANTS (VACCINIUM CORYMBOSUM L.)

Potted, two-year-old bushes of 'Bluecrop' and 'Jersey' were taken through two stress/recovery cycles in the greenhouse in which severely (≤-80 cb) and moderately (-60 to -70 cb) water stressed plants were compared to a well-watered (≥-30 cb) control. Plants were rewatered after each stress event. Gas exchange measurements were made during stress and after recovery. Vegetative measurements were made after each stress/recovery cycle and plants were divided and dried for partitioning analysis at the conclusion of the experiment.

While gas exchange rates were significantly reduced in stressed plants during each of two cycles of soil moisture stress, normal gas exchange rates were observed after recovery. After two cycles of stress, stressed plants had significantly reduced leaf numbers and individual and whole plant leaf areas compared to controls. Stressed plants allocated a significantly higher percentage of dry matter to their root systems at the expense of above-ground growth.